The primary objective of this pilot study is to determine the safety and toxicity of weekly Herceptin and paclitaxel given preoperatively followed by adriamycin and cyclophosphamide (AC) postoperatively in patients with Her-2 overexpressing locally advanced breast cancer. Secondary objectives are to estimate tumor response and to make preliminary observations on the effect of treatment by Herceptin-paclitaxel on tumor histology and to explore potential molecular determinants of response to this preoperative regimen.